The objective of this study is to determine whether or not the presence of cell surface receptors for shigella exotoxin determines the susceptibility of various cell types to its action. Of particular interest is the differential response of small and large bowel tissue which respectively are sensitive and resistant to lumenal toxin. If a receptor determines the toxin effect in the pathogenesis of clinical shigellosis control measures based on the receptor-ligand interaction become feasible. In the context of these studies the nature of the cell membrane receptor will be studied and the kinetics of binding determined using various cell lines in monolayer culture and organ culture. BIBLIOGRAPHIC REFERENCES: Keusch, G.T. Bacterial toxins viewed as virulence factors: Shiga bacillus dysentery viewed as a toxinosis. Mt. Sinai J. Med 43: 33-41, 1976. Keusch, G.T., Jacewicz, M. The Pathogenesis of Shigella diarrhea. VI. Toxin and anti-toxin in Shigella flexneri and Shigella sonnei infections in humans. J. Infect. Dis. 135:552-556, 1977.